It is well known that the life expectancy of a well-designed engine, correctly operated, tuned and lubricated, depends to a large extent on how well its running conditions are adapted to the filtration of air, fuel and oil. The methods of filtration employed, as an example in automotive engines, are determined by the minimum efficiency required for each type of engine and the nature of the contaminating materials. It is also well known that the presence of water and suspended solid debris or other contaminants in diesel and gasoline injection fuel delivery systems causes severe damage to delicate injection pumps and injector nozzles. Experience has shown as much care and vigilance must be given to the design of a fuel delivery filtration system so that of air and oil if the engine is to perform satisfactorily.
An important purpose of in-tank fuel strainers or filters is to serve as impermeable barriers to aqueous solutions as present in fuel and suspended debris whose presence within the engine could cause excessive wear or malfunction of the engine parts. Fuel filters also provide two other equally important functions in high speed compressive engines of the automotive type. First, they exclude entry of air into the fuel stream whenever the air-fuel interface is below the entrance of the fuel pick-up tube. Finally, variable fuel consumption requirements of the engine mean that the filter must act as a conduit and transmit sufficient fuel to the engine for all operating conditions, even though the fuel level is low.
The filter or strainer design, used as standard equipment on many American vehicles, is a square mesh plain-weave fabric sleeve attached to the fuel pump or the fuel pick-up line. The fabric sleeve has on its interior a tubular mesh support of the type employed in the present invention. Th textile fabric employed in the prior art as well as in the present invention is usually made from Saran (TM) polyester fabric or from polyvinylidene chloride (PVdC) thread because such polymers do not swell or decompose when immersed in hydrocarbons and water. A variety of PVdC and PVdC polyester reinforced fabrics are commercially available and have been used to alter the basic filter design for specific vehicle applications.
A problem with existing fuel filters of the type described has been that the connector outlet of the filter has not been sealed with the results that contaminants or debris upon or within the interior of the filter pass through the filter outlet with the gasoline into the fuel delivery system to thereby cause damage to the delicate injunction pumps, fuel pumps and injector nozzles. It is possible for debris or contaminants to get into the interior of the fuel filter as a result of edges or chips breaking off from the open mesh plastic support located within the fabric body. In addition, it is possible for contaminants to get into the interior of the filter at the time the filter is manufactured even though care is usually taken to prevent such contamination of the fuel filter. The internal support can be broken at the time the filter is installed within the fuel tank reservoir or when it is used in a free floating environment as in U.S. Pat. No. 4,303,513. Thus, any contaminants which accumulate within the interior of the filter is free to pass along with the gasoline or fuel through the non-filtered outlet into the fuel line resulting in clogged fuel pumps, ejectors and other malfunctions of the vehicle engine.
A filter of the general type disclosed herein, is shown in the Robert J. Lundquist's U.S. Pat. No. 4,303,513, dated Dec. 1, 1981 entitled "Duel Pick-up Fuel Strainer Assembly".